#include<iostream>
 #include<stack>
 #include<algorithm>
 using namespace std;
 char a[100001];
 int i,op,jy=1;
 stack<int> gtb; 
 int main(){
	 while((op=getchar())!='@')
	 {
		 if(a[i]=='.')
		 {
			for(int j=i-1;j>=0&&a[i]>='0'&&a[i]<=9;j--)
			gtb.push(op);
			continue;
		 }
		 if(a[i]>='0'&&a[i]<='9')
		 continue;
		 op=gtb.top();
		 gtb.pop();
		if(a[i]=='+') op=gtb.top()+op;
		if(a[i]=='-') op=gtb.top()-op;
		if(a[i]=='*') op=gtb.top()*op;
		if(a[i]=='/') op=gtb.top()/op;
		gtb.pop();
		gtb.push(op);
	 }
	 cout<<gtb.top();
 }